Pulmonary Function Tests

2. Pulmonary Function Tests

3. Classification • Obstructive lung disease(pattern): COPD,Asthma,Bronchiolitis ,Bronchiectasis • Restrictive lung disease(pattern) ILD,NMD,…

4. Pulmonary Function Tests Spirometry Body Plethysmography (Body Box) Body Box + Dlco Metacholine Challenge text(MCT) Cardiopulmonary Exercise Test (Ergospirometry)

5. Spirometry

7. Spirometry Flow Loop- Normal

8. Flow Volume Loop

9. What information does a spirometer yield? • A spirometer can be used to measure the following: • FVC and its derivatives (such as FEV1, FEF 25-75%) • Peak expiratory flow rate • Maximum voluntary ventilation (MVV) • Slow VC • IC, IRV, and ERV • Pre and post bronchodilator studies

10. Information Provided by the Spirometer The ratio of FEV1/FVC is normally between 0.7 and 0.8. Values below 0.7 are a marker of airway obstruction, except in older adults where values 0.65–0.7 may be normal. In people over 70 years old, the FEV1/FVC ratio may need to be lowered to 0.65 as a lower limit of normal. conversely, in people under 45, using a ratio of 0.7 may result in under-diagnosis of airway obstruction.

11. INTERPRETATION Interpretation of spirometry involves looking at the absolute values of FEV1, FVC, and FEV1/FVC, comparing them with predicted values, and examining the shape of the spirograms. Patients should complete three blows that are consistent and within 5% of each other—many electronic spirometers automatically provide this information.

13. Spirometry Quality

14. Upper Airway Obstruction

15. Bronchodilator Reversibility Testing Bronchodilator reversibility testing is best done as a planned procedure, as it is time consuming. If the patient is undiagnosed and on no therapy, acute reversibility can be assessed on the first visit. Short-acting bronchodilators need to be withheld for at least 4 hours prior to testing, and long-acting bronchodilators for 12 hours. Recent treatment with inhaled glucocorticosteroids can also reduce bronchodilator reversibility because the pre-bronchodilator FEV1 may improve significantly with Inhaled glucocorticoid therapy.

16. Reversibility testing Spirometry should be undertaken when the patient is clinically stable and free from a respiratory tract infection. Short-acting bronchodilators should be withheld for the previous 6 hours, long-acting bronchodilators for 12 hours, and sustained release theophylline for 24 hours. FEV1/FVC should be measured before and 15-20 minutes after bronchodilator is given. The bronchodilator should be given by metered dose inhaler, ideally through a spacer. A nebulizer may be used but generally larger doses are delivered by this route. The dose administered should be high on the dose-response curve. Possible dose protocols include 400 μgsalbutamol, up to 160 μgipratropium, or the two combined.

17. Pre-Post Bronchodilator ATS recommends a positive response is > 12% improvement in FEV1

18. Patterns of Spirometric Curves NORMAL: FEV1 and FVC above 80% predicted FEV1/FVC ratio above 0.7 OBSTRUCTIVE: FEV1 below 80% predicted FVC can be normal or reduced – usually to a lesser degree than FEV1 FEV1/FVC ratio below 0.7 RESTRICTIVE: FEV1 below 80% predicted FVC below 80% predicted FEV1/FVC ratio normal - above 0.7.

20. Spirometry (Indication) 1- Evaluate dyspnea 2- Detect Pulmonary Diseases 3- Monitoring of Treatment 4- Evaluate Preoperative Risk 5- Evaluate respiratory impairment 6- Surveillance for occupational lung diseases

21. Spirometry (Contraindaction) 1- Hemoptysis 2- Pneumothorax 3- Recent MI (UA) 4- Aortic Aneurysm 5- Cerebral Aneurysm 6- Recent eye surgery 7- Recent thoracic & abdominal surgery

22. Body plethysmography

23. Body plethysmography • The most accurate way • The patient sits inside a fully enclosed rigid box and breath through mouthpiece connected through a shutter to the internal volume of the box • while breathing in and out again into a mouthpiece. The volume of all gas within the thorax can be measured by Changes in pressure inside the box and allow determination of the lung volume( Boyles Law)

24. These parameters will be evaluated by Body Box: • Residual volume (RV) • Tidal volume (TV) • Total Lung Capacity (TLC) • Expiratory reserve volume (ERV) • Inspiratory Reserve Volume (IRV) • Inspiratory capacity (IC) • Functional residual capacity (FRC) • Vital Capacity (VC)

25. Diffusing Capacity(Dlco) • Diffusing capacity of lungs for CO • Measures ability of lungs to transport inhaled gas from alveoli to pulmonary capillaries • Depends on: - alveolar—capillary membrane - hemoglobin concentration - cardiac output

26. Decreased DLCO(<80% predicted) Obstructive lung disease Parenchymal disease Pulmonary vascular disease Anemia Increased DLCO (>120-140% predicted) Asthma (or normal) Pulmonary hemorrhage Polycythemia Left to right shunt Diffusing Capacity

27. DLCO — Indications • Emphysema • Evaluation and severity of restrictive lung disease • Early stages of pulmonary hypertension

29. Methacholine Challenge Test

30. Bronchoprovocation testing INDICATIONS: • accurate diagnosis of bronchial asthma • assessment of the response to asthma therapy • identification of triggers for environmental or occupational asthma.

31. Methacholine challenge • A series of methacholine chloride solutions are prepared, ranging from approximately 0.05 mg/mL to 25 mg/mL being administered by nebulizer. • After inhalation of the aerosol, the FEV1 is measured at 1, 3, 5, and 10 minutes, and the concentration is increased one step until a 20 percent decrease in FEV1 or a 35 or 40 percent decrease in specific airways conductance (SGaw) is observed • The dose that provokes a 20 percent drop in FEV1 is referred to as the PC20. Generally, a PC20 of 8 mg/ml methacholine or less is considered a positive test

32. CPET(Ergospirometry)

33. Indications for Exercise Testing • Diseases that affect the heart, lungs, circulation, or blood shortness of breath that otherwise cannot be determined at rest or through conventional lung function testing • exercise capacity and anaerobic threshold of the individual abnormal blood pressure response to exercise Follow responses to therapy in patients with cardiopulmonary disease poor circulation

34. Patterns of abnormal response to exercise in different diseases